Description: This Core was approved at the previous review but did not become operational until two years ago, due to "restriction in funding". The core performs routine and non-research diagnostic enzymology and molecular analysis in tissues (usually cultured fibroblasts) derived from patients suspected to have inherited metabolic disorders of research interest to the center investigators, including glutaric acidemia type I (glutaryl-CoA dehydrogenase deficiency, GCD), glutaric acidemia type II (ETF-ubiquinone oxidoreductase or ETF-QO deficiency), and homocystinuria (cystathionine beta-synthase or CBS deficiency). Molecular diagnosis has started only very recently, and six cell lines have been analyzed for various mutations in the glutaryl-CoA dehydrogenase gene. The purpose of this core is to relieve investigators from the need of conducting these rather labor-intensive specialized assays while providing them with tissues from accurately diagnosed patients. It is expected that the number of requests for molecular analysis will increase in the future.